Celebrities including James McVey from The Vamps and Hollywood actor Will Poulter have spoken out about being bullied as part of a Back2School anti-bullying campaign.
As 10 million children in the UK return to class for the start of the new academic year, g uitarist McVey and The Revenant star Poulter supported The Diana Award initiative by sharing their own school photos, experiences, and offering advice to pupils.
The charity is encouraging people of all ages to post or share a picture of themselves at school - past or present - on social media, with their back to school advice, using the hashtag #Back2School.
Almost two thirds of people who were bullied at school face a lasting impact on their confidence and self esteem, according to The Diana Award.
A YouGov survey commissioned by the charity found that just over a third of those bullied - 35% - said it negatively affected their ability to trust other people.
Nearly two thirds - 64% - of people who were bullied while in education said it negatively affected their confidence, while 60% said it had a negative impact on their self-esteem.
Some 35% believed bullying behaviour was happening in their current place of work. Over half of adults - 56% - are said to have experienced bullying at school.
The Diana Award works to give young people, professionals and parents the skills, confidence and training to tackle all forms of bullying as Anti-Bullying Ambassadors.
Others supporting the drive include former England footballer Rio Ferdinand, singer Jessie J and Diversity dancer Ashley Banjo.
McVey revealed in a video how he would be punched in the stomach and threatened in the corridors.
"One of them said he would kill me and cut me up. I found that really, really difficult to deal with... In hindsight to them, they probably didn't see it as that big of a deal... But to me, at the receiving end of that, it was quite traumatic. It made that time at school really really difficult," he said.
Giving his back to school advice, he added: "Be confident within yourself - but if you do witness bullying... make sure that you let someone else know. It's really, really important to tackle it in the early stages."
Poulter, who appeared in the sci-fi movie The Maze Runner, said: "A lot of the things that were said or done to me that I guess I would consider bullying. I didn't realise how much they would affect me until later on.
"The insecurities and lack of confidence that I developed in my adult years I attribute to things that occurred at school."
He added: "It's important you don't fear school or you feel that it is bigger than you. School is a small part of your entire life and you are bigger. There is a lot more to life."
Alex Holmes, head of the Diana Award Anti-Bullying Campaign, said: "School should be safe and free from bullying. We're urging everyone to get behind our campaign by helping us to train Anti-Bullying Ambassadors in schools."
The launch comes just a few days after the 19th anniversary of the death of Diana, Princess of Wales.
The charity was set up in memory of the Duke of Cambridge and Prince Harry's mother after she was killed in a Paris car crash in 1997.
More information about Back2School, including an online advice centre, can be found at www.antibullyingpro.com.